Colonel

Colonel, the highest field-grade officer, ranking just below the general officer grades in most armies or below brigadier in the British services. A colonel was traditionally the commanding officer of a regiment or brigade. In air forces with the same titles of rank as the army, such as the U.S. Air Force, a colonel’s command is usually a group; the comparable grade in the Royal Air Force is group captain. When not exercising command of a regiment, group, or equivalent formation, a colonel is generally placed in a senior staff or administrative post [Encyclopedia Britannica].
A kernel is the edible portion of a seed, nut, or fruit inside a stone or shell. The kernel may also mean the essential part of something. The kernel comes from the Old English word cyrnel, which means seed or pip. A colonel is a high-ranking officer in an army or air force. A colonel ranks higher than a lieutenant colonel and below a brigadier general. Colonel comes into the English language in the sixteenth century from the Middle French coronel, influenced by the Italian word colonnella, meaning commander of a column of soldiers at the head of a regiment [Grammatist].

Sources:

British army officer, topographer, and antiquary. Encyclopedia Britannica. Retrieved from: https://www.britannica.com/topic/colonel

Kernel vs colonel Homophones Spelling & Definition. Grammatist. Retrieved from: https://grammarist.com/homophones/kernel-vs-colonel/